Complete Geographic Distribution: Introduced in northeastern North America, originally from Europe. North American populations include Greenland, Canada (Quebec, Ontario, Nova Scotia, New Brunswick (Newfoundland), and the United States (Michigan, West Virginia, Pennsylvania, New York, Vermont, New Hampshire, and Maine). Eastern hemisphere populations can be found throughout Europe, Central Asia, Siberia, Pakistan and Kashmir (4, 6, 13).

Vegetative Plant Description: Herbaceous climbing vine with alternate, pinnately compound leaves. Each leaf bears 4-8 pairs of leaflets and has branched tendrils at the tip of the leaf, replacing any terminal leaflets. The leaflets are emarginate or ovate, with an acute or mucronate tip. Stipules are small and coarsely toothed. Pulvini are present at the petiole base. The plant has nitrogen-fixing bacteria in its roots (5, 12, 17).

Flower Description: The blue-purple or occasionally white flowers are 8-15 mm long and grow in sessile or almost sessile inflorescences of 2-6 flowers. Each pedicel is slightly longer than the inflorescence peduncle. The fused calyx is irregular and forms a glabrous or villous tube 4-5mm long, with the two upper sepals distinctly shorter than the lower three. The calyx is deeper in color than the zygomorphic corolla, which is also 5-parted. The lower two petals form a keel, and the wings of the corolla adhere to the middle of the keel. The style is filiform and hairy, and the stamens are more or less diadelphous (5, 6, 17).

Flowering Time: June – September (12)

Pollinator: A study from Scotland that included V. sepium indicated that certain bees choose plants with corollas longer than the bees’ tongues for nectar (1). Two bumblebees, Bombus pasuorum and B. sylvarum have been suggested as pollinators, as well as Autographa gamma, a moth (15).

Distinguished by: V. sepium can be distinguished from V. cracca, and V. villosa by its sessile or nearly sessile inflorescences. V. cracca and villosa have long peduncles. Additionally, V. cracca has a very symmetrical calyx quite different than the irregular calyx of V. sepium, and V. villosa has 10+ flowers per raceme, unlike the 2-6 flowers of the inflorescences of V. sepium.
While V. sativa has similar inflorescences to V. sepium, the calyx of V. sativa is regular. V. hirsuta has distinctly peduncled inflorescences (6, 17).V. sepium can be most accurately distinguished from members of the genus Lathyrus by its styles and stamen-tubes. The styles of Vicia are pubescent or villous at the apex; those of Lathyrus are pubescent or villous along the entire upper side of the style. Additionally, the stamen tubes of all Vicia members “terminate obliquely” whereas those of Lathyrus are truncate. A final character that may possibly distinguish Vicia from Lathyrus is the stems – Lathyrus members often have winged stems, unlike V. sepium (6, 17).

Phylogenetic Information: V. sepium is a member of the subfamily Faboideae within the family Fabaceae. Fabaceae, along with the Polygalaceae, Quillajaceae, and Surianaceae form the Fabales order. The Fabales, Rosales, Cucurbitales, and Fagales form a monophyletic clade within the Eurosids I within the larger Rosid group of the Eudicot angiosperms (16).

Interesting Quotation or Other Interesting Factoid not inserted above: The elevational distribution of this species has changed since 1905. Optimum elevation currently is about 1,100 m, whereas in 1905 it was closer to 1,000 m (11).
Voss (6) mentions only two collections made in Michigan, one from 1915 in Detroit, and the second from Isle Royale in 1959.

Literature and websites used:

Brian, A.D. Differences in the Flowers Visited by Four Species of Bumble-Bees and Their Causes. 1957. Journal of Animal Ecology 26(1): 71-98.

Fernald, M. L. and A. Gray. 1950. Gray’s Manual of Botany: a handbook of the flowering plants and ferns of the central and northeastern United States and adjacent Canada. 8th ed. Portland, Oregon, Dioscorides Press, 1632p.

ANGIOSPERM PHYLOGENY GROUP 2003. An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG II. Botanical Journal of the Linnaean Society 141(4): 399-436.

Gleason, H.A. 1963. The New Britton and Brown Illustrated Flora of the Northeastern United States and Adjacent Canada. New York, New York, USA: Hafner Publishing Co., Inc.